The prior art double-sided auxiliary lock includes a locking core, a reinforcing plate and a surface lid. The locking core is installed with a plurality of screw holes. The locking core is combined with an auxiliary lock at an inner side by a plurality of positioning elements passing through the screw holes. The reinforcing plate has a via hole to which the surface lid is attached. The surface lid is formed with a post which can extend through the via hole of the reinforcing plate. The surface lid is disposed at an outer side of the locking core.
In above mentioned prior art, the locking core has the effect of preventing the double-sided auxiliary lock from being destroyed, but in a surface of the auxiliary lock, the positioning elements assembled in an inner side of the double-sided auxiliary lock is exposed. Thereby, the positioning elements are still possibly destroyed. Moreover, the exposed positioning elements will result in a poor appearance of the double-sided auxiliary lock. Thus, there is an eager demand for a novel design which can improve the prior art defects.